Exposure to peanuts builds immunity in allergic children

With the caveat that this should not be tried at home, researchers conducting a study in children with peanut allergies found that the participants could build up a tolerance by consuming increasingly larger amounts of peanut protein on a regular basis.

The technique, called oral immunotherapy (OIT), was used as part of the STOP II trial, results of which are published in The Lancet.

Allergies to peanuts are quite common, and symptoms can range from mild to severe. A more serious, possibly life-threatening reaction is called anaphylaxis, which can cause swelling of the throat and mouth or changes to the heart rate.

The researchers, from the UK, note that the only current way to prevent severe reactions in children allergic to peanuts is for them to completely avoid foods that contain them.

However, accidental reactions are common, says the team, with yearly incidences of 14-55%.

To combat this, the researchers followed 99 children with peanut allergies who were between the ages of 7 and 16 years. These children were randomly assigned to one of two groups:

Group 1: received 26 weeks of OIT using gradually increasing doses of peanut protein - up to 800 mg each day

Group 2: was instructed to follow the current standard of care, which is to avoid peanuts completely.

After 6 months of oral immunotherapy, nearly all of the children could safely consume the equivalent of five peanuts.

After 6 months, the children all took part in a double-blind placebo-controlled food challenge, where they gradually consumed increasing amounts of peanut protein.

It should be noted that they were under medical supervision at all times, and researchers noted at what level they encountered allergic symptoms.

In the second part of the trial, the second group (control group) was also offered 26 weeks of OIT before another food challenge.

Majority could consume equivalent of five peanuts

After 6 months of OIT, 62% of the children passed the food challenge and were able to tolerate a daily dose of 1,400 mg of peanut protein, which is around 10 peanuts, whereas the control group was not.

However, after the second phase of the trial, when all children had undergone OIT, 54% were able to tolerate the food challenge.

Additionally, after 6 months of the therapy, 84-91% of the children could safely consume 800 mg of peanut protein, which is around five peanuts. This is 25 times the amount they could tolerate before the therapy.

Study leader Dr. Andrew Clark, from Cambridge University Hospitals in the UK, says:

"This treatment allowed children with all severities of peanut allergy to eat large quantities of peanuts, well above the levels found in contaminated snacks and meals, freeing them and their parents from the fear of a potentially life-threatening allergic reaction."

Around a fifth of the children who received OIT reported adverse events, through these were mostly mild. In one patient, who withdrew from the trial, adrenaline was used to treat symptoms after only two doses of OIT.

OIT 'should only be done by medical professionals'

The oral immunotherapy technique was successful in the latest trial, and Dr. Pamela Ewan, co-author from the study, says it is "an important advance in peanut allergy research."

But Dr. Ewan cautions:

"However, further studies in wider populations are needed. It is important to note that OIT is not a treatment people should try on their own and should only be done by medical professionals in specialist settings."

In a linked editorial to the study, Matthew J. Greenhawt, from the University of Michigan Food Allergy Center, adds that this technique is experimental, writing that "OIT is not ready for clinical use until the short-term effects have been comprehensively proven."

But the researchers are pleased with their positive results, as are the parents of the children.

"The families involved in this study say that it has changed their lives dramatically," says Dr. Clark.

Because quality of life is reduced in many sufferers of peanut allergies due to the threat of anaphylaxis, providing a way to neutralize this threat could be very helpful, the team adds.

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